Telephone system



E. W. FLINT TELEPHONE SYSTEM Nov. 4, 1941.

5 Sheets-Sheet l Filed April 5 /Nl/E/vron E. W. FL//VT A 7" TODA/EV Nov. 4, 1941. E. w. FLINT TELEPHONE SYSTEM Filed April 3, 1940 5 Sheets-Sheet 2 A T TOR/VEV Nov. 4, 1941. E. w. FLINT 2,261,243

TELEPHONE SYSTEM Filed April 3, 1940 5 Sheets-Sheet 3 Nov. 4, 1941. E. w. FLINT 2,251,243

TELEPHONE SYSTEM Filed April 3, 1940 5 Shee'lzS--Sheefl 4 22a F/G. 4 TRANSFER c//ecU/T 45.3

/M/EN To By E'. W. FL /N 7 Nov. 4, 1941.

E. W. FLlN-T TELEPHONE ySYSTEM FAiled Anpril 3, 1940 5 Sheets- Sheet 5 /A/l/E/V TOR @y E. W. FL /N r A 7 ToRA/Ey .Ph mw f!! m 4 m SSG .N w3 059B .Emi

Patented Nov. 4, 1941 UNITED STATES E PATENT orifice TELEPHONE SYSTEM Erlon W. Flint, Mountain View, N. J., assigner to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application April 3, 1940, Serial No. 327,556

' 5 claims. .(01.179-27) This invention relates to telephone systems and has for its object to increase the flexibility of such systems.

During. the transformation of telephone service in large centers from a manual basis to a dial ,f

basis, it has become apparent that many people are physically or psychologically incapable of handling the dial. In general, dial ofces are so arranged that, when the initiation of a call is not followed by the operation of the dial, after a measured interval the call will be directed to an operator. The use of this method for avoiding dialing involves delay and usually directs the ,call to the attention of a trouble operator.

In accordance with the present invention means is provided, responsive to the initiation of a call, which immediately transmits an operator code to the central oflice equipment which responds thereto to connect the calling line with an operators position.

This equipment is common to a number of lines and is individualized to a calling line only if idle. A plurality of groups of lines each served by a dialing equipment may, in case of trouble, be combined in one group.

These and other features of the invention will y be more apparent from a consideration of the following detailed description in connection with the drawings in which:

Fig. l shows a calling line and, in diagrammatic v Fig. 4 shows a transfer circuit' and a second For a complete description lof a dial'central nl' oice with which the present invention would function, reference is hereby made to Patent 2,235,803, granted March 18, 1941, to W. W. Carpenter.

substation |00 is connected to one of a subgroup of ten manual lines in a group served by the dialing circuit of the present invention. This circuit is connected between the subscribers line and the normal connection of the line to the line link frame. When a call is initiated on this line, the line relay |02 is operated in a circuit from battery through its winding, inner back contact of hold magnet |0I, lower normal contacts of relay |03 over the line and substation circuit, upper normal contacts of relay |03 to ground at the outer back contact of hold magnet |0|. The operation of line relay |02 initiates the operation of the line link and sender link control circuits which connect the line with an idle sender |08 and an idle district junctor |09.

When the hold magnet I0| is operated, its 0perating ground is extended to conductor |04, upper back contact of relay |05, winding of relay |03 and battery. Relay |03 operates and connects ground to conductor |06 to mark the line busy to terminating calls. At its upper and lower normal contacts, it disconnects substation |00 from the line link to prevent dial tone from reaching the subscriber, and at its alternate contacts connects resistance |01 over the lower back contact of relay |05 to the link to hold the connection with the sender |08.

At its inner upper front contact, relay |03 connects ground to conductor l0 to seize the dialing circuit. If no other group is attempting to seize the dialing circuit, a circuit is closed from ground on conductor ||0, winding of relay of the iirst group of lines, normal contacts of the intermediate group start relays, normal contacts of relay ||2 of the last group of lines, conductor |28, outer lower back contact of relay 400, conductor 428 to battery. Relay operates, locking to battery at its own right alternate contact. At its left front contact it closes a circuit from battery throughthe winding of group'connecting relay ||3 to conductor ||4 which extends, if the dialing circuit is idle, over the outer lower back contact of relay 200 to ground at the upper back contact of relay 20|. At the same contact it opens the operating circuit of group connecting relay ||5 of the last group as well as of the corresponding intermediate relays.

From a consideration of Fig. 1, it will appear that'the group start relay of an intermediate or last -group may be operated, while the first group is being served, but that theY corresponding group connecting relays cannot operate until the first group start relay releases.

Relay ||3 at its second contact connects ground to conductor |I8, lower back Contact of relay 20| to the winding of relay 203 and battery.

'Relay 203 connects ground over its inner upper contact to the circuit of relay I3.

With relays ||3 and 203operated a circuit is closed from battery through resistance ||6, first contact of relay ||3, inner lower frontcontact of relay 03, outer contact of relay ||`3, conductor |1, lowermost contact of relay 202,winding of relay 2 |0, normal contacts of. relays 2|5 and 2|9, to

ground at the outer upper contact of relay 203. Relay 2|0 locks to ground at its upper alternate contact and extends the dialing circuit to the sender. Relays 2|0 to 2|9 are individual to the ten lines of a group and serve in combination with the group connecting relay to individualize the dialing circuit to a particular line. As in the case of the group relays, the lower numbered relays operate over normal contacts of the higher numbered relays so that more than one relay of the chain may operate but the lowest numbered relay is effective rst.

Relay I |3 also connects ground over its third contact to conductor I I9, thereby starting the P- eration of the polarized pulsing relays 300 and 30|. Two circuits normally exist through relays 300 and 30|, one from battery through resistance 308, tip contact of jack 303, winding of relay 300, resistance 304, upper winding of relay 30|, ring contact of jack 303, resistance 306 to battery. The second circuit extends from battery through resistances 308 and 302, condenser 301, inner auxiliary contact of jack 303, lower winding of relay 30|, outer auxiliary contact of jack 303 to battery through resistance 306. With battery connected to both sides of the relay windings, the relays are inert. When conductor I I9 is grounded, it shunts battery through resistances 302 and 308, thereby energizing the upper winding of relay 30| in a direction to close the relay contact, but the charging current for condenser 301 opposes that in the upper winding so that the closure of the contact is delayed a definite time. Grounded conductor ||9 is also connected to the armature of relay 30| and when the contact closes it connects ground in shunt of battery through resistance 306. The upper winding is now energized to open the relay contact, but the discharge current from condenser 301 delays the opening. Relay 300 operates in synchronism with relay 30|, alternately connecting ground to conductors 309 and 3|0.

When the sender is ready to receive a registration it connects ground and battery to the dialing circuit, thereby completing a circuit from ground over the tip contacts of the sender link and line link, upper alternate contacts of relay |03, contact |20 of relay I I3, conductor |2I, middle upper front contact of relay 2|0, conductor 204, back contact of relay 3|I, conductor 3|2, winding of relay 205, inner lower front contact of relay 2|0, conductor 206, contact |22 of relay 3, lower alternate contact of relay |03, over the ring contacts of the line link and sender link to battery in the sender. Relay 205 operates in this circuit and closes a circuit from battery through the winding of relay 201, upper front contact of relay 205, outer upper front contact of relay 2|0, conductor 208, contact |23 of relay 3, to the operating circuit of relay |03 which is grounded over the sleeves of the links from the sender |08.

If the Sleeve ground is properly closed, relay 201 operates, and locks over its outer upper front contact, through resistance 209 to ground at the lower front contact of relay 203. It also closes a locking circuit over its second upper front contact to its operating circuit independent of relay 205. With relay 201 operated, a circuit is closed from battery through the winding of relay |05, contact |24 of relay ||3, conductor |25, outer lower front contact of relay 2 I0, third and fourth upper front contacts of relay 201, resistance 209 to ground at the lower front contact of relay 203. Relay operates in this circuit locking over its upper front contact to conductor |04 and opening the circuit of relay |03. However, relay |03 is held operated over contact |23 of relay ||3, conductor 208, upper front contact of relay 2|0, second and third upper contacts of relay 201, outer lower front contact of relay 2|0, conductor |25, contact |24 of relay H3, front contact of relay |05 to ground over the link holding circuit. Relay I 05 disconnects resistance |01 from across the dialing circuit.

Relay 201 closes a circuit from battery through the winding of relay 220, inner upper front contact of relay 201 over the back contacts of relays 3|3 and 32| to 330 to ground on conductor IIS, to determine that the pulse counting circuit is normal. Relay 220 operates and locks over its inner upper` contact and the outer upper back contact of relay 330 to grounded conductor ||8. At its outer upper front contact relay 220 closes an obvious circuit for relay 20|, and at its lower front contact connects ground over the inner lower front contact of relay 201 to the holding circuit of relay ||3. Relay 20| connects ground over its upper front contact and the inner lower back contact of relay 330 to conductor I3 and opens the circuit of relay 203 which releases slowly in order to delay the start of pulsing sufficiently to allow any pulse caused by switching the line at relay |03 to register as a preliminary pulse rather than to be added to the chain of ten pulses which follows.

When relay 203 releases it closes a circuit from battery through the winding of relay 3|3, lower front contact of relay 20|, lower contact of relay 205, lower back contact of relay 203, lower back contacts of relays 32| to 330, to conductor 3|0. When relay 300 closes its left contact, connecting ground to conductor 3|0, relay 3|3 operates, locking over its outer upper front contact and the outer upper back contacts of relays 32| to 330 to grounded conductor IIB.

When relay 300 closes its right contact, grounding conductor 309, it completes a circuit over the outer lower front contact of relay 3|3 to the winding of relay 3|| and battery. Relay 3I| opens the dialing circuit to transmit a pulse to sender |08, closes a temporary holding circuit Ior relay 3|3 at its outer upper contact and an operating circuit for relay 32| which may be traced from ground over the inner upper contact of relay 3| I, inner lower front contact of relay 3|3 to the winding of relay 32| and battery. Relay 32| operates and locks over its outer upper front contact and the back contacts of relays 325, 329, 330, etc., to conductor I|8 and opens the locking circuit of relay 3|3 but that relay is held until the termination of the pulse when relay 3| I releases, reclosing the dialing circuit and in turn releasing relay 3 3.

The next closure of ground to conductor 300 operates relay 3|| over the outer lower front contact of relay 32|. Relay 3|| opens the dialing circuit to transmit the second pulse, closes a holding circuit for relay 32| and an operating circuit for the next counting relay, which in operating opens the locking circuit of relay 32| leaving the latter relay under the control of relay 3||. The remaining eight pulses are sent in a similar manner, relay 3I| opening and closing the line under the control of relay 300. When relay 329 operates, it closes at its outer upper front contact a shunt around the back contact of relay 330 thereby maintaining the holding cir- Cult of relay 220 until the end of the tenth pulse. Relay 330 in operating closes a circuit from battery through the winding of relay 20|,

upper front contacts f of o relay '330 to iconduc-tor H8, 'tohold relay-520| AAp'ela'itcl Funder the controlo'f relayy I |31.A RelayA 330locks :over itslowe'r front contact to ground atthe upper? front 'coni tact ofrelay l f I' Y A;

Relay 220Y is Inadeslow to -release to prevent any accidental pulse, Ydue tof transferring the tipfand ring leadsbacki'to theV subscribers line, from lregistering 'as an eleventh.pulse;` When rel'ay 220 releases, `relay |`|3 V is released, opening the circuit'0fre1ays*|n3,'z|o, zurgzcsy and zul, and removing ground from 'conductor I |8, Relay l|I3 also removes ground yfrom `conductor I I9 to stop the pulsing r`elays." Relay 120| is slow to release to prevent a secondgroup connecting jf relay from operatinguntilrelay I I3 has opened its contacts. When relayZUI releases, relay ,330 releases and thecircuit for lthe fnext groupnconnecting'relay is prepared;

The release of. relay A|03 restoresjthe connection of the substationline V'to thecentral office equipment.4 Wth'the digit Zer'owrecorded'in `the sender,l the marker |26 is seizedover` the marker connector and an operators position'I21'is connected to the junctor |00, -The subscriber may now give the wanted number Ato the operator at position |21 who is provided jwith means for completing the connection.

During the dialing operation, the substation is disconnected from the central olce equipment and the abandonment of the call is ineffective.

However, there are some conditions which may cause the sender link to time out, thus producing a condition similar to an abandoned call.

If the dialing circuit fails to close, relay 205 cannot operate and timed release by the link control circuit, removing ground from conductor |04 permits all operated relays to release and places the circuit in condition for another call.

If the sender link control circuit remo-Ves ground from conductor |04 before relay 201 closes its holding circuit .the relays may all release. If ground is removed from conductor |04 after relay 201 has operated, the link hold magnets will remain operated under the control of relay 203, but when relay 203 releases, relays 201, |03 and |05 release, in turn releasing relays |I| and II3.

To guard against failures in the dialing circuit itself, two pulse circuits are provided, each normally serving a. plurality of groups of lines. However, in case of trouble either pulse circuit may serve all of the line groups and means is provided for automatically transferring the line groups. For this purpose the grounding of conductor II8, as above described, applies ground to the armature of interrupter 22|. When the interrupter closes its upper contact, it operates relay 222 which locks to conductor II8. If the call is completed and the circuit restores to normal in the next five seconds, the locking ground is removed and relay 222 releases. If not, when the interrupter closes its lower contact ground is extended over the lower front Contact of relay 222, conductor 223, upper back contact of transfer relay 400 of the second pulse circuit, conductor 450, winding of transfer relay 200 and loat-` tery. Relay 200 locks over its inner lower front contact to ground on key 45|. Relay 200 operates relay 202 which opens the circuits of relays 2|0 to 2|9 and lights lamp 224. With relays 202 and 200 operated a circuit is closed from ground at the inner upper front contact of relay 202, second upper contact of relay 200, connects conductors ductor. 452;!l back contact of relay 453,." winding of r'eli'a'y `45'4to'lbattery. Relayv 454 operates' and connects tlie'circuits` controlled by the group connecting relays of the first dialing circuit in parallel 'with' .those-ofthe seconddialing circuit. Relay-200 also "prepares'a circuity for relay 453 under the controlof interrupterl42l of the secondlfdialingcircuit', and -closes la circuit from ground over the normal contact of jack225, middle lower frontv contact of relay 200,"to conductor 226 leading to an alarm. A I i I 'I'he` two-setsof grouprelays now form one group, the circuit of-thegroup start relays of the operative dialingl circuit extending e over the contacts of" thegr'oup start relays of the disabled dialing circuit. The circuit'of relay 5| I, for example, .extends from ground in the associated line circuit,4 winding of relay 5|I, normal contactsof the'intermediate group start relays and relay 5|2, conductor 228, front Acontact of relay 200, conductor |29, normalA contacts of the group start relays III-I I2, etc., of the first dialing circuit, conductor -|'28,'ba`ck` contacty of relay 400, conductor 428 to battery.` The circuit of relay 'I I3 extends-over the front contactof relay III, conductor`|| 4,vlower frontcontactof relay 200, conductor 221Vto the back contact of vgroup start relay 5|2-of the last group /oflines served by` the second dialing circuit and over the back contacts of the other line group relays 5| I, etc., to conductor 5|4 leading to the second dialing circuit. Similarly, if the second dialing circuit were disabled, conductor 5|4 would be extended over a front contact of transfer relay 400 to conductor 421 and the back contact of the last line group relay of the first dialing circuit. Therefore, the group connecting relays of the two dialing circuits form one chain, with the relays of the disabled dialing circuit having later choice than those of the working circuit.

If both dialing circuits time out, relay 453 is operated over the front contact of the transfer relay of one circuit and the lower contact of the timing interrupter of the other circuit. Relay 453 locks to key 45|, lights lamp 455, sounds an alarm and releases relay 454 to open the connection between the dialing circuits. It also con- I28 and 288 to permit the operative dialing circuit to continue to function.

When the line of substation |00 is called, the terminating marker grounds conductor |06, operating relay |05 over the inner upper back contact of relay |03. Relay |05 extends its operating ground over conductor |04 tothe winding of the line hold magnet. This magnet and relay |05 are held over the sleeve of the link under the control of theincoming junctor and thereby ground conductor |06 after the marker releases. With relay |05 operated, relay |03 cannot operate and the dialing circuit is not affected b-y a terminating call.

What is claimed is:

1. In a telephone system, telephone lines, operators positions, and means for automatically connecting one of said telephone lines with one of saidoperators positions comprising switching equipment, control means for operating said swltching equipment and means automatically responsive to the initiation of a call by said one telephone line to automatically generate and transmit a series of impulses representing an operator code to said control means, said control means responsive to said operator code to cause said switching equipment to connect said line with an operators position.

2. In a telephone system, telephone lines, operators positions, and means for automatically connecting one of said telephone lines with one of said operators positions comprising switching equipment, control means for operating said switching equipment and means common to a plurality of said lines automatically responsive to the initiation of a call on one of said plurality of lines to automatically transmit an operator code to said control means.

3. In a telephone system, telephone lines, operators positions, and means for automatically connecting one of said telephone lines with one of said operators positions comprising switching equipment, control means for operating said switching equipment, impulse generating means.

common to a plurality of said lines and means automatically responsive to the initiation of a call on one of said plurality of lines to cause said impulse generating means to transmit an operator code to said control means.

4. In a telephone system, telephone lines equipped with dials, other telephone lines without dials, operators positions, switches, equipment for controlling said switches, means responsive to the initiation of a call on any one of said lines to connect said line with said control equipment, and means common to a plurality of said other telephone lines for extending one of-said other lines to one of said operators positions, comprising impulse generating means, means associated with said impulse generating means for disconnecting said control equipment from said line and for connecting said control equipment to said impulse generating means, means for causing said impulse generating means to transmit an operators code to said control equipment for causing said control equipment to extend said line to an operators position whereupon said operator may `extend said line to a wanted line. y

5. In a telephone system, telephone lines arranged in groups, impulse generating means common to said groups of lines, means for individualizing said impulse generating means to one of said lines comprising a `connecting relay individual to each group of lines, said relays arranged in a chain circuit, other groups of lines, a second impulse generating means common to said other groups of lines, a chain of connecting relays individual to said other groups of lines, and means effective in case of trouble with one of said impulse generating means to connect said chains of relays into a single chain, the chain individual to the faulty impulse generating device occupying the less favored position in the combined chain.

ERLON W. FLINT 

